Numerical Rounding Rules for Medicare

Posted October 26, 2012

Recently several questions have arisen about how to handle reporting test results and determining coverage when the values are not whole numbers. This most often occurs for oxygen saturation results (either arterial blood gas or pulse oximetry) and sleep tests where the apnea/hypopnea index (AHI) or respiratory disturbance index (RDI) results are expressed with a decimal place.

In both of these instances, standard numerical rounding rules apply. For example, consider a sleep test where the AHI is reported as below:

If the value is 12.01 to 12.49, round down to 12

If the value is 12.50 to 12.99, round up to 13.

The only exceptions to this rule are where Medicare policy makes clear that the specified level is absolute and rounding is not to be used. One such situation is in the completion of Question 5 on the Oxygen Certificate of Medical Necessity ("Enter the highest oxygen flow rate ordered for this patient in liters per minute. If less than 1 LPM, enter an ‘X'."). No rounding is allowed for flow rates less than 1.0.

Last Updated May 23 , 2017